610 EXPERIMENT STATION RECORD. 



(I']. S. K.. 22. I). niO) lliiil tlir error is Irnm <I.12 to ().:.:; iiiu'. lie tln'rcforc (Iccins 

 incorrect. 



The determination of colloids in clays, K. Kndki.i, {'/Jscliv. cIkhi. h. Indus. 

 Kolloiilc, 5 (Hmt), p. ^',',; titt.s. in Chcm. /Jfj., S.i (I'.KJH), Xo. I')!!, Rcitni., p. 

 (n.')). — The dry clay is boiled witli Canada balsam, and after cooling and 

 hardening it is cnt into small sections and colored with fuchsin. By photo- 

 gr.iphing th(> sections the areas can be located which contain the colloids 

 (Si(X., AL.O,,, I'\\.0.,). These are cut out .-ind weighed. 



Studies for the determination of phosphoric acid in phosphatic slags and 

 natural phosphates by the citro-mechanical method, E. Guerry and E. Tous- 

 s.viNT (/}///. ISoc. Cliim. Bvhj., 23 {1909), \o. IJ, pp. //.5.'/-//57).— This is a fnrther 

 study of the method previously noted (E, S. R., 18, p. 107). 



The authors now propose the following jtrocedure: Two and five-tenths gm. 

 of the material are placed in a 250 cc. Jena liask with about 20 to 25 cc. concen- 

 trated sulphuric acid and heated, care being taken not to allow the material 

 to adhere to the sides of the flask. The mixture is kept boiling for 10 minutes, 

 then allowed to cool somewhat, water added in small quantities, cooled again, 

 filled up to the mark with water, and filtered. Twenty-five cc. of the filtrate 

 are then taken in a beaker, neutralized with ammonia, allowed to cool, and 

 SO cc. of ammonium citrate solution (containing 10 gm. of citric acid), and 15 

 cc. of concentrated ammonium hydroxid added. After placing in a shaking 

 apparatus, 35 cc. of magnesium mixture is added dropwise. the mixture shaken 

 again for 25 minutes, filtered, and the precipitate washed with dilute ammonia 

 and ignited as usual. 



A study of the methods for the determination of iron and alumina in 

 phosphate rock, W. C. Dumas (Amer. Fert., 31 (1909), No. 5, pp. 7-i//).— The 

 author concludes from his work " that there is no more error due to impurities 

 in the Glaser alcohol method than there is in the acetate method, and that this 

 error seldom amounts to IG per cent." It is further shown that a combination 

 of the Glaser alcohol and acetate methods furnishes very good results, and that 

 it consumes no more time than either of these alone. It is advisable to remove 

 flnorin in solution in the acetate method as the results run low, and the iron 

 should be present in the ferric state. 



" In the Glaser alcohol method the calcium salts should be precipitated in a 

 50 per cent alcohol solution, containing considerable excess of free HCl. When 

 the phosphates are precipitated by ammonia, only the slightest excess is per- 

 missible. . . . Blasting the FePOj and AIPO4 is not necessary if they are 

 ignited strongly over the Bunsen burner for 15 minutes. The Glaser alcohol is 

 the best method of all for iron and aluminum in the hands of the inexperienced." 



The determination of iron and alumina in inorganic plant constituents, 

 XL F. Hare {■Jour. Indus, and Engin. ('Ik in., 2 [1910), Xo. 1, pp. 27. 2S).— 

 Owing to the fact that the Association of Official Agricultural Chemists have 

 no official method for the determination of iron and alumina in the presence of 

 phosphorus in inorganic plant constituents, the author proposes a method which 

 yields satisfactory results and which is not so troublesome as the methods 

 usually recommended by others. The methods of separating the 2 elements are 

 described and a method for determining the iron is also given. 



Two volumetric methods for determining calcium and magnesium, V. 

 ScHENKE (Chcm. Ztfj., S3 (1909), Xo. 150, pp. 1313, i Ji// ) .—These methods allow 

 the determination of lime and magnesia and lime alone, in gray limes, raw or 

 burnt lime, lime ashes, marls, soils, and silt. 



The first method consists of adding to 2.5 to 5 gm. of material 125 cc. normal 

 hydrochloric acid in a 250 cc. long-necked flask, and allowing this to stand upon 

 the boiling water bath for at least one-half hour, and then filling to the mark 



